When first rendered, if more items appear than can render in maxRows, all of those items flash on screen for a frame or so length of time before disappearing. You can see this by starting with the example-code and copy/pasting the "categories" values like 8 more times. To see the problem you'll need to get the widget to re-build, e.g. by running your code on desktop (Windows, in my case) and making some change to your main.dart file (a space and then Ctrl-S works for me).
When first rendered, if more items appear than can render in maxRows, all of those items flash on screen for a frame or so length of time before disappearing. You can see this by starting with the example-code and copy/pasting the "categories" values like 8 more times. To see the problem you'll need to get the widget to re-build, e.g. by running your code on desktop (Windows, in my case) and making some change to your main.dart file (a space and then Ctrl-S works for me).